1. Field
The disclosed concept relates to vacuum switching apparatus and, in particular, vacuum switching apparatus such as, for example, vacuum interrupters. The disclosed concept also relates to electrode extension assemblies and assembly methods for vacuum interrupters.
2. Background Information
Some circuit breakers such as, for example, power circuit breakers, employ vacuum interrupters as the switching devices. Vacuum interrupters generally include separable electrical contacts disposed on the ends of corresponding electrodes within an insulating housing. Typically, one of the contacts is fixed relative to both the housing and to an external electrical conductor, which is electrically interconnected with a power circuit associated with the vacuum interrupter. The other contact is part of a movable contact assembly including an electrode stem of circular cross-section and a contact disposed on one end of the electrode stem and enclosed within a vacuum chamber. A driving mechanism is disposed on the other end, external to the vacuum chamber. The electrodes are typically brazed or otherwise suitable joined together when the vacuum interrupter is made.
The external ends of the electrodes (i.e., electrode stems) are relatively limited in their capability for use in various different vacuum interrupter designs and ability to meet customer design requirements. Further, there are a number of potential problems associated with modifying electrode stems after the vacuum interrupter has been otherwise assembled (i.e., after the vacuum envelope has been sealed). For example, oxidation of the electrodes can occur, and/or a connection having undesirably low electrical and thermal conductivity or damage to the sealed vacuum envelope could result.
There is, therefore, room for improvement in vacuum switching apparatus, such as vacuum interrupters, and in electrode extension assemblies and associated assembly methods therefor.